Method and apparatus for securing electrode-supporting studs on the envelope of a color cathode ray tube

ABSTRACT

This disclosure depicts method and apparatus useful in the manufacture of color cathode ray tubes of the type having a color selection electrode supported in spaced relationship to a faceplate portion of the tube envelope. More particularly, this disclosure depicts method and apparatus for securing on the envelope studs employed in supporting the electrode. By the use of an alignment fixture, there is positioned and held on an inner surface of the envelope at the intended location of the studs, jigs which temporarily support the studs at the precise intended locations thereof. The jigs are temporarily secured to the envelope inner surface by the use of an air-hardenable, room temperature cement such that the studs are accurately and firmly held at the said precise locations. The alignment fixture is then removed and a cement of a type which cures at high temperature is located between the studs and the envelope inner surface. The faceplate with the jigs attached is baked to cure the high temperature cement and thereby permanently affix the studs to the envelope. Finally, the jigs are broken loose and removed from the envelope to leave the studs permanently cemented to the envelope. The jigsg and alignment fixtures are disclosed in detail.

United States Patent [191 Rogers METHOD AND APPARATUS FOR SECURINGELECTRODE-SUPPORTING STUDS ON THE ENVELOPE OF A COLOR CATHODE RAY TUBE[75] Inventor: Melvin F. Rogers, Western Springs,

[73] Assignee: Zenith Radio Corporation, Chicago,

Ill.

[22] Filed: Dec. 21, 1973 [21] Appl. No.: 427,389

Primary ExaminerEdward G. Whitby Attorney, Agent, or Firm-John H. CoultOQO 000 000000 00 1 Oct..14, 1975 ABSTRACT This disclosure depictsmethod and apparatus useful in the manufacture of color cathode raytubes of the type having a color selection electrode supported in spacedrelationship to a faceplate portion of the tube envelope. Moreparticularly, this disclosure depicts method and apparatus for securingon the envelope studs employed in supporting the electrode. By the useof an alignment fixture, there is positioned and held on an innersurface of the envelope at the intended location of the studs, jigswhich temporarily support the studs at the precise intended locationsthereof, The jigs are temporarily secured to the envelope inner surfaceby the use of an air-hardenable, room temperature cement such that thestuds are accurately and firmly held at the said precise locations, Thealignment fixture is then removed and a cement of a type which cures athigh temperature is located between the studs and the envelope innersurface. The faceplate with the jigs attached is baked to cure the hightemperature cement and thereby permanently affix the studs to theenvelope. Finally, the jigs are broken loose and removed from theenvelope to leave the studs permanently cemented to the envelope. Thejigsg and alignment fixtures are disclosed in detail.

10 Claims, 11 Drawing Figures US. Patent Oct. 14, 1975 Sheet 1 of53,912,564

I US. Patent Oct. 14, 1975 Sheet2of5 3,912 564 US. Patent Oct. 14,1975Sheet 5 of5 METHOD AND APPARATUS FOR SECURING ELECTRODE-SUPPORTING STUDSON THE ENVELOPE OF A COLOR CATHODE RAY TUBE CROSS REFERENCE TO RELATEDAPPLICATIONS This application relates to, but is in no way dependentupon, copending applications including Ser. No. 535,473, filed Dec. 23,1974 (a continuation-in-part of now-abandoned application Ser. No.395,106, filed Sept. 7, 1973); Ser. No. 395,334, filed Sept. 7, 1973;Ser. No. 424,017, filed Dec. 12, 1973; and Ser. No. 498,836, filed Aug.19, 1974 (a continuation of nowabandoned Ser. No. 285,985, filed Sept.5, 1972 BACKGROUND OF THE INVENTION It is well known that studs forsupporting the color selection electrode of a color tube adjacent thefaceplate thereof may be secured to the envelope inner surface by theuse of a high temperature cement such as the devitrifying solder glass,commonly termed frit. For example, see U.S. Pat. Nos. 2,727,172 and2,846,608.

One of the drawbacks of this method of securing studs to a color tubeenvelope has involved the burdensome restaints imposed on the fixtureused to position and hold the studs during the high temperaturecementing operation. Due to the long bake cycle required to curefrit-type cements (typically l-3 hours), the requirement that analignment fixture be provided to hold the studs in place during the bakecycle means that a great many fixtures must be provided to satisfy thedemands of a high volume production facility. For example, a color tubefacility producing 10,000 tubes per day would require between 1,000 and2,000 such fixtures, with attendant storage, handling and capital costburdens.

Further, because the typical bake cycle is conducted at temperatures inthe range of 400500C, such a fixture must be capable of maintaining therequired stud positioning tolerances (typically a few mils) whileundergoing such extreme temperature cycles. It is well known that it isextremely difficult to maintain such high tolerances with a fixturesubjected to extreme temperature cycling, and that to attempt to do soinevitably will result in high fixture maintenance and replacementcosts.

OBJECTS OF THE INVENTION It is a general object of this invention toprovide improved method and apparatus for cementing electrodesupportingstuds on the envelope of a color cathode ray tube.

More particularly, it is an object to provide such improved method andapparatus which does not require the temperature cycling of an alignmentfixture used to position the studs on the tube envelope.

It is another object to provide improved method and apparatus forcementing electrode-supporting studs on the envelope of a color cathoderay tube which provides high positioning accuracy for the studs, and yetwhich result is achieved at a relatively modest cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspectiveview, partly broken away, of one corner of a color cathode ray tube,illustrating a color selection electrode and a suspension devicetherefor, which suspension device employs an electrode-supporting studof the type with which this invention is most advantageously involved;

FIGS. 2-7 are views of a novel jig employed in a studcementing methodaccording to this invention;

FIGS. 8-10 are plan, sectional, elevational and fragmentary perspectiveviews illustrating an alignment fixture employed in the method of thisinvention; and

FIG. 11 is a view showing a portion of the FIGS. 2-7 jig as it wouldappear at one step in the method of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a fragmentaryperspective view of one corner of a color cathode ray tube including acolor selec tion electrode 10 supported by suspension devices (one ofwhich is shown at 12) incorporating a stud of a type with which theprinciples of this invention are applicable. The stud 14 has a bodyportion 16 and a foot 18 which is adapted to be cemented to the innersurface 20 of a faceplate 22. The faceplate 22 is adapted to mate with afunnel 24 constituting the remaining portion of the tube envelope. Thebody portion 16 of the stud 14 has formed therein an opening 26 which isadapted to receive a spring-biased lug 28 carried on the distal end of aspring 30 held by a supporting bracket 32.

As is well known, the color selection electrode 10 must be supportedadjacent the faceplate 22 at a critical distance from the inner surface20 of the faceplate and also must be positioned in the planeperpendicular to the tube axis with a high degree of positionalaccuracy. Thus, the studs 14 must be located on the faceplate 22 with ahigh degree of accuracy, typically in the order of a few mils or lessfor conventional tubes, and in the case of tubes fabricated withinterchangeable masks, to accuracies of a few tenths of a mil.

The suspension device 12 forms no part of this invention, but representsan invention described and claimed in referent copending applicationSer. Nos. 424,017, 498,836 and 535,473, assigned to the assignee of thepresent invention. The illustrated color selection electrode 10 alsoconstitutes no part of this invention but is disclosed and claimed incopending application Ser. No. 395,334, filed Sept. 7, 1973, alsoassigned to the assignee of the present invention.

This invention is directed to an improved method and associatedapparatus for cementing electrodesupporting studs, for example studs ofthe type shown at 14 in FIG. 1, upon the inner surface of a colorcathode ray tube envelope. Whereas the principles of this invention aremost advantageously employed to cement studs directly on the faceplateof a flangeless-type faceplate as shown in FIG. 1, the principles ofthis invention may also be applied to cement studs on the faceplate orflange portions of flanged front panels and on color tube envelopes ofother types.

At the heart of this invention is the use of a jig 34, shown withparticular clarity in FIGS. 2-7 which is adapted to be temporarilysecured to the inner surface of the associated color tube envelope toaccurately position and hold the stud during a high temperaturecementing operation in which the stud is permanently cemented to theenvelope. As will be described in detail below, the jig 34 is cementedto the envelope by the use of a room temperature, air-hardenable cementwhich holds the stud during the high temperature cementing operation,thus obviating the use of a high accuracy alignment fixture to hold thestuds during the high temperature cementing operation. As will bedescribed in detail hereinafter, the jig 34 is positioned and held in analignment fixture (shown at 36 in FIGS. 8-10) which places the jig onthe faceplate with a high degree of dimensional accuracy. Beforediscussing the fixture 36 and associated stud cementing method, however,the jig 34 will be described in detail.

The jig 34 comprises stud holding means for releaseably gripping thestud 14, guide means for slideably receiving the stud holding means andthe stud, and means for urging the stud into firm engagement with theinner surface of the tube envelope. In the illustrated preferredembodiment, the means for urging the stud into firm engagement with thefaceplate during the high temperature cementing operation (described indetail below) takes the form of an elongated body 38 having apredetermined mass by which a gravitational force is exerted on thestud. In the illustrated embodiment, the stud holding means is shown astaking the form of a clamp, comprising a clamping bar 40 through which atightening screw 42 is passed for reception in a threaded bore in a baseportion 44 of the body 38. When the screw 42 is drawn tight, a head 46on the clamping bar 40 makes frictional engagement with a flat surface47 on the body 38 and a foot 48 on the clamping bar 40 makes frictionalengagement with body portion 16 of the stud 14. The stud 14 is ths heldin firm connection with the body 38.

In the illustrated preferred embodiment, the guide means is shown astaking the form of a sheet metal guide 50 having a circular opening 52in a first leg 53 for slideably receiving the body 38 and a rectangularopening 54 in a second leg 56 axially spaced from the first leg 53 forslideably receiving the body portion 16 of the stud 14. It is thus seenthat with the clamping bar 40 drawn tight to innerconnect the body 38and the stud 14, the coupled body-stud assembly is free to slidevertically in the guide 50.

The guide 50 is provided with a pedestal 58, here shown as comprisingthree legs 60, 62, 64 which are adapted to be temporarily cemented tothe inner surface of the faceplate 22 by means of an airhardenable, roomtemperature cement. It is noted that the legs 60-64 are dimensioned, andthe bottom surface of the foot 18 of the stud 14 is configured to followthe curvature of the inner surface 20 of the faceplate 22 such that theaxis of the jig 34 is parallel to the tube axis.

As will be described in detail hereinafter, in accordance with themethod of this invention, a high temperature cement, preferably of theso-called frit-type, is employed to permanently cement the stud 14 tothe faceplate 22. In accordance with a preferred implementation of thisinvention, a measured quantity of frit cement, preferably in the form ofa dry pellet 72, is inserted beneath the floating gravity-biasedstud-body assembly after the jig 34 has been cemented to the faceplate22.

As briefly discussed above, in accordance with this invention, a novelalignment fixture 36 is provided for positioning the jigs 34 (and thusthe studs held thereby) with a high degree of accuracy at spaced pointson the faceplate 22 while the jigs 34 are being cemented to the innersurface 20 of the faceplate 22. See FIGS. 8-10.

In the illustrated preferred embodiment, the alignment fixture 36 isshown as comprising a chassis, here shown as taking the form of a baseplate 74, which acts to provide a rigid skeleton for the fixture andwhich serves to carry associated attachments and components. The fixture36 includes means carried by the faceplate 22 for detachably engagingthe outer peripheral edge 76 of the faceplate 22, acting as a referenceedge, and for aligning the fixture 36 relative to the faceplate 22 inthe X-Y plane perpendicular to the faceplate axis. The means forassuring alignment of the fixture relative to the faceplate in the saidX-Y plane is shown as comprising three cylindrical locators 78, 80, and82. The locators depend from the base plate 74 and make engagement withthe faceplate 22 at three spaced points on the peripheral edge 76 of thefaceplate. To draw the locators 78-82 into firm engagement with theperipheral edge 76 of the faceplate 22, there is provided two clampassemblies 84, 86. Each of the clamp assemblies 84, 86 includes anL-shaped support bar 88 which carries a spring-biased piston 90, on theoperative end of which piston is located a bumper 92 making contact witha point on the peripheral edge 76 of the faceplate 22. When the piston90 is released, by rotating it to the release position shown in FIGS.8-9, the piston 90 is free to travel under the influence of the spring93. The bumper 92 thus engages the faceplate peripheral edge 76 anddraws the fixture locators 78-82 into firm engagement with the faceplateperipheral edge 76.

To locate the base plate 74 of the fixture 36 at a predeterminedelevation from the faceplate 22, there is provided a plurality of feet(here shown as three in number) 94, 96, 98 which engage the innersurface 20 of the faceplate 22 and support the base plate 74 at apredetermined distance from the faceplate 22.

A plurality of jig-holding bars 100 are mounted on the base plate 74 andserve to releaseably position and hold the jigs 34. Mounting bolts 102,104 provide for detachment of the jig-holding bars 100 from the jigs 34after the jigs 34 have been cemented to the inner surface of thefaceplate.

The jig-holding bars include on one end thereof a pair of spaced fingers106, 108, the separating space between which is contoured to conform tothe crosssectional configuration of the body 38. Because of the flats110, 112 formed on the body 38, the body is not free to rotate betweenthe fingers 106, 108. A set screw 109 passing through finger 106 andinto the threaded bore 1 1 1 holds the jigs 34 firmly on the jig-holdingbars 100.

As will be described in more detail below, by this arrangement, afterthe jigs 34 have been cemented to the faceplate 22, the jig-holding bars100 can be loosened from the base plate 74 and slipped radially off thejigs 34, permitting the alignment fixture 36 to be removed.

A method for cementing electrode-supporting studs on the envelope of acolor cathode ray tube following the principles of this invention willnow be described in detail. The first step of a perferred method is toinsert the studs 14 into four jigs 34 and to draw the screws 42 up toeffect a tight clamping of the studs 34 against the bodies 38. The jigs34 are then mounted on the jigholding bars 100 which are in turn boltedonto the base plate 74.

The alignment fixture 36 with the jigs 34 held thereby is then placed onthe concave inner surface of a faceplate 22 and the clamp assemblies 84,86 released to draw the locators 78-82 into firm engagement with theenvelope peripheral edge 76. With the jigs 34 positioned at the intendedlocation of the studs 14, the jigs 34 are adhered securely to theenvelope inner surface by the use of an air-hardenable room temperaturecement. Satisfactory results have been obtained using a cement of asoluble silicate binder base variety with an inorganic particulatefiller, e.g., Sauerusen No. 31 eement made by Sauerusen Cement Co.,Pittsburgh, Pennsylvania. Using a cement of the type described, thecement may be permitted to dry at room temperature for the recommendeddrying time, typically -30 minutes, or, in the interest of hastening thedrying process, the cement may be irradiated with infra-red radiationthrough the faceplate from the front side thereof. It has been foundthat the cement-hardening process can be hastened from 203O minutes tol-3 minutes by the application of infra-red radiation as described.

With the jig now cemented on the faceplate with a high degree ofpositional accuracy, the jig-holding bars 100 are loosened and slippedoff the jigs 34, permitting the alignment fixture 36 to be removed.

A measured quantity of frit, preferably in dry pellet form as shown at72, is inserted under the foot 18 of each stud 14. It is noted at thispoint that the clamped stud-body assembly is free to move against theforce of gravity in the guide 50. Thus, to insert the frit pellet 72 thestud-body assembly is merely lifted and the pellet placed beneath.

The faceplate 22 with attached jigs 34 is then placed in an oven andbaked to cure the frit cement. By way of example, using a frit cement ofthe devitrifying solder glass type, the faceplate is preferably baked ata temperature in the range of 400-450 for approximately one hour. Duringthe bake cycle, the frit pellet 72 liquifies. Because of the biasapplied to the stud during the baking operation, here shown as beingaccomplished by the use of a weight acted upon by the force of gravity,the stud 14 is urged through the frit cement into firm engagement withthe inner surface 20 of the faceplate 22.

The faceplate 22 with attached jigs 34 is then removed from the oven andcooled to room temperature. The clamping bars 40 are released and thebody 38 removed. The remaining portion of the jig 34, namely the guide50-pedestal S8, and the stud 14 then appear as shown in FIG. 11. Theguide-pedestal is then broken loose and removed from the faceplate. Thusthe studs 14 remain, permanently cemented to the faceplate with a highdegree of positional accuracy.

It is seen then that by this invention, a stud cementing method andapparatus are provided by which the alignment fixture 36 performs itsalignment functions always at room temperature and does not have to gothrough any thermal cycling. Further, because the alignment fixture 36is employed only for the length of time required to harden theair-hardenable cement used to adhere the jigs 34 to the faceplate 22,the alignment fixture 36 has a relatively short duty cycle and can beused hundreds of times during each working day. By the obviation of anythermal cycling of the alignment fixture, the alignment fixturemaintains its high dimensional accuracy substantially indefinitely,resulting in substantial economies in the stud cementing operation.

The invention is not limited to the particular details of constructionof the embodiments depicted and other modifications and applications arecontemplated. For example, whereas the above-described method andapparatus have been depicted as applied to the cementing of studs onto aflangeless-type face-plate, the principles of this invention may beemployed to cement studs onto the inner surface of the flanges of aflanged-type faceplate. For example, it is contemplated that theprinciples of this invention may be implemented using jigs of otherconstructions than shown and described above. Jigs having other studholding, guiding and biasing structures may be employed. Spring biasrather than gravitational bias may be used, for example. Alignmentfixtures other than the fixture 36 portrayed above may be employed. Theabove-described studcementing method is preferred, however modificationsof this method within the teachings of the invention, and rearrangementof the steps in the afore-described method may be employed. Certainother changes may be made in the above-described methods and apparatuswithout departing from the true spirit and scope of the invention hereininvolved and it is intended that the subject matter in the abovedepiction shall be interpreted as illustrative and not in a limitingsense.

I claim:

1. For use in the manufacture of color cathode ray tubes of the type ishaving a color section electrode supported in spaced relationship to afaceplate portion of the cathode ray tube envelope, a jig adapted to betemporarily secured to the inner surface of the cathode ray tubeenvelope to accurately position and hold an electrode-supporting studduring a high temperature cementing operation in which the stud ispermanently cemented to the envelope, said jig comprising:

stud-holding means for gripping said stud;

guide means for slideably receiving said stud-holding means and the studwhile connected, said guide means having support means for engaging theenvelope inner surface to support the jig, said support means beingadapted to be temporarily cemented to the cathode ray tube envelope bymeans of an air-hardenable cement; and

means for urging the stud through the stud cement into firm engagementwith the envelope inner surface during the high temperature cementingoperation.

2. The apparatus defined by claim 1 wherein said stud-holding meansincludes an elongated body having a predetermined mass, said bodyconstituting said means for urging the stud, by the force of gravityacting on said mass, into engagement with the envelope inner surface.

3. The apparatus defined by claim 2 wherein said stud-holding meansincludes a clamp for clamping said body to the stud.

4. The apparatus defined by claim 3 wherein said guide defines first andsecond openings spaced on a slide axis for slideably receiving said bodyportion and a shank portion of the stud.

5. The apparatus defined by claim 1 wherein said support means comprisesa plurality of feet which engage the envelope inner surface and areadapted to be individually cemented thereto.

6. In the manufacture of color cathode ray tubes of the type having acolor selection electrode supported in spaced relationship to afaceplate portion of the tube envelope, a method for securing on theenvelope studs which are employed in supporting the electrode,comprising:

gripping the studs with respective jigs;

by the use of an alignment fixture, positioning and holding the jigs onan inner surface of the envelope at the intended locations of the studsto temporarily support the studs at the precise intended locationsthereof;

securely adhering the jigs to the envelope inner surface by the use ofan air-hardenable, room temperature cement such that the studs areaccurately and firmly held at said precise locations;

removing the alignment fixture;

locating between the studs and the envelope inner surface a cement of atype which cures at high tem perature;

baking the faceplate with the jigs attached to cure the high temperaturecement and thereby permanently affix the studs to the envelope; and

breaking loose and removing the jigs from the envelope to leave thestuds permanently cemented to the envelope.

7. The method defined by claim 6 wherein the jigs each have a pluralityof discrete feet which engage the envelope inner surface, and whereinsaid step of adhering comprises cementing the feet individually to theenvelope.

8. The method defined by claim 6 wherein said method includes positivelyurging the stud through the temperature cement is a devitrifying solderglass which cures at temperatures above 400F, and wherein the time andtemperature of the baking operation are sufficiently long to cure saidcement.

10. For use in the manufacture of color cathode ray tubes of the typehaving a color selection electrode supported in spaced relationship to aflangeless faceplate comprising part of the tube envelope, an alignmentfixture for accurately positioning and firmly holding on the faceplate aplurality of jigs which are adapted to be temporarily secured to theinner surface of the faceplate and which act to accurately position andhold an electrode-supporting stud during a high temperature studcementing operation, said alignment fixture comprising:

a chassis;

means carried by said chassis for detachably engaging the outerperiphery of the faceplate which acts as a reference edge, and foraligning said fixture relative to the faceplate in a plane perpendicularto the faceplate axis;

means carried by said chassis and engaging the surface of the faceplatefor supporting the jig on the faceplate;

a plurality of jig-holding means carried by said chassis for positioningand releaseably holding a like plurality of jigs on the faceplate innersurface; and

means providing for detachment of said jig-holding means from said jigsbefore a faceplate baking operation, but after an operation in which thejigs are cemented temporarily to the inner surface of the faceplate.

high temperature cement during the baking operation and into intimateengagement with the envelope inner surface.

9. The method defined by claim 6 wherein the high

1. For use in the manufacture of color cathode ray tubes of the type ishaving a color section electrode supported in spaced relationship to afaceplate portion of the cathode ray tube envelope, a jig adapted to betemporarily secured to the inner surface of the cathode ray tubeenvelope to accurately position and hold an electrode-supporting studduring a high temperature cementing operation in which the stud ispermanently cemented to the envelope, said jig comprising: stud-holdingmeans for gripping said stud; guide means for slideably receiving saidstud-holding means and the stud while connected, said guide means havingsupport means for engaging the envelope inner surface to support thejig, said support means being adapted to be temporarily cemented to thecathode ray tube envelope by means of an air-hardenable cement; andmeans for urging the stud through the stud cement into firm engagementwith the envelope inner surface during the high temperature cementingoperation.
 2. The apparatus defined by claim 1 wherein said stud-holdingmeans includes an elongated body having a predetermined mass, said bodyconstituting said means for urging the stud, by the force of gravityacting on said mass, into engagement with the envelope inner surface. 3.The apparatus defined by claim 2 wherein said stud-holding meansincludes a clamp for clamping said body to the stud.
 4. The apparatusdefined by claim 3 wherein said guide defines first and second openingsspaced on a slide axis for slideably receiving said body portion and ashank portion of the stud.
 5. The apparatus defined by claim 1 whereinsaid support means comprises a plurality of feet which engage theenvelope inner surface and are adapted to be individually cementedthereto.
 6. IN THE MANUFATURE OF COLOR CATHODE RAY TUBES OF THE TYPEHAVING A COLOR SELECTION ELECTRODE SUPPORTED IN SPACED RELATIONSHIP TO AFACEPLATE PORTION OF THE TUBE ENVELOPE, A METHOD FOR SECURING ON THEENVELOPE STUDS WHICH ARE EMPLOYED IN SUPPORTING THE ELECTRODE,COMPRISING: GRIPPING THE STUDS WITH RESPECTIVE JIGS, BY THE USE OF ANALIGMENT FIXTURE, POSITIONING AND HOLDING THE JIGS ON AN INNER SURFACEOF THE ENVELOPE AT THE INTENDED LOCATIONS OF THE STUDS TO TEMPORARILYSUPPORT THE STUDS AT THE PRECISE INTENDED LOCATIONS THEREOF, SECURELYADHERING THE JIGS TO THE ENVELOPE INNER SURFACE BY THE USE OF ANAIR-HARDENABLE, ROOM TEMPERATURE CEMENT SUCH THAT THE STUDS AREACCURATELY AND FIRMLY HELD AT SAID PRECISE LOCATIONS, REMOVING THEALIGMENT FIXTURE, LOCATING BETWEEN THE STUDS AND THE ENVELOPE INNERSURFACE A CEMENT OF A TYPE WHICH CURES AT HIGH TEMPERATURE, BAKING THEFACEPLATE WITH THE JIGS ATTACHED TO CURE THE HIGH TEMPERATURE CEMENT ANDTHERBY PERMANENTLY AFFIX THE STUDS TO THE ENVELOPE, AND BREAKING ANDREMOVING THE JIGS FROM THE ENVELOPE TO LEAVE THE STUDS PERMANENTLYCEMENTED TO THE ENVELOPE.
 7. The method defined by claim 6 wherein thejigs each have a plurality of discrete feet which engage the envelopeinner surface, and wherein said step of adhering comprises cementing thefeet individually to the envelope.
 8. The method defined by claim 6wherein said method includes positively urging the stud through the hightemperature cement during the baking operation and into intimateengagement with the envelope inner surface.
 9. The method defined byclaim 6 wherein the high temperature cement is a devitrifying solderglass which cures at temperatures above 400*F, and wherein the time andtemperature of the baking operation are sufficiently long to cure saidcement.
 10. For use in the manufacture of color cathode ray tubes of thetype having a color selection electrode supported in spaced relationshipto a flangeless faceplate comprising part of the tube envelope, analignment fixture for accurately positioning and firmly holding on thefaceplate a pluRality of jigs which are adapted to be temporarilysecured to the inner surface of the faceplate and which act toaccurately position and hold an electrode-supporting stud during a hightemperature stud cementing operation, said alignment fixture comprising:a chassis; means carried by said chassis for detachably engaging theouter periphery of the faceplate which acts as a reference edge, and foraligning said fixture relative to the faceplate in a plane perpendicularto the faceplate axis; means carried by said chassis and engaging thesurface of the faceplate for supporting the jig on the faceplate; aplurality of jig-holding means carried by said chassis for positioningand releaseably holding a like plurality of jigs on the faceplate innersurface; and means providing for detachment of said jig-holding meansfrom said jigs before a faceplate baking operation, but after anoperation in which the jigs are cemented temporarily to the innersurface of the faceplate.